How do proteins regulate the expression of specific genes? If we could understand this then someday we might modify abnormalities in gene transcription associated with development, differentiation and a broad spectrum of diseases including cancer. An important area of current investigation in our efforts to understand the mechanism of cellular control and development is the nature and operation of protein-nucleic acid interactions. The basic objective of this proposal is to design and synthesize cleavable protein-nucelic acid cross-linking reagents which will be useful to thee molecular biologists in their efforts to understand how proteins recognize nucleic acid. Similarly, we propose to synthesize nucleic acid-nucleic acid crosslinkers in order to examine the question of DNA and RNA packaging in viruses.